Owner has seen this thread
http://community.whathifi.com/forums/t/313192.aspx
and would rather I looked at it rather than the maker

Easy to blame PbF as printed all over as such.
Problem is different to that above thread. For ages now the R ch has failed
occassionally at switch on. Switch off and most of the time it comes up.
Very rarely that ch dies in use, Then last week both ch failed at sw on , so
he decided something needed doing

Anyone know how to find mechanical data on 16 amp output relays
Make Finder 40.615 , clear cased so can see the contact gaps
About .75mm for the R one and .5mm or so for the L. Thinking fine contact
contamination and not enough mechanical punch-through.
Both relays in series from one supply and TA3717 ptotector IC
Or any other ideas other than checking phones socket, if wired in to affect
output somehow, PbF solder looks fine. Wanging with engraver and nylon bolt
has only highlighted a microphonic capacitor.

Looks like another amp where I'll make an LED mod that the owner can view
through the phones socket. Bring out pcb mounted, relays-on LED ,and add a
different colour one for the main rails supplies on, both viewable through
the phones socket transparent plastic panel at its rear